Just gathering some opinions ..
While I appreciate the 'it's your car ....' sentiment I thought I'd get some opinions from the mini fraternity
In two minds about my completely original 1970 mini K. Thinking about tasteful modifications to draw a little more power and improve stopping (eg:exhaust, carb, disc brakes etc) but wondering if it's better that this car be preserved in its original state.
If it were an original Cooper I wouldn't be asking but I'm not sure about the 'rarity' of unmodified aus built cars and what also might affect resale value.
Car even has original service manual, receipts going way back etc etc.
Any thoughts appreciated

I like original cars, but if it's only exhaust,carb and brakes, i say do it. Keep the original parts and if needed it can be back to original over a lazy weekend

All the parts you mention are bolt on mods. Very easy to unbolt to go back to original. You will need to alter the rear brakes if you put discs on the front. Just be wary that disc brakes will widen the track around an inch per side. Wheel choices become limited without flares.

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

All good advice. Keep in mind that the alterations on the rear brakes simply means changing the wheel cylinders - a simple part swap that can be reversed if that's ever required.

Thanks folks -good points made here

My mini K has been owned from new in 1969. I had the same thoughts as you are having.
As a young person I always wanted it 'to go faster' and experimented with the usual mods. I made a lot of mistakes but learnt a lot in the process.
It now has: a 1275 motor, twin HS2, extractor and cooper S sized exhaust, K gearbox, S disc brakes/booster and LS Contesta wheels (that don't need flares).
It is a"happy" car to drive, lots of enjoyment as it does all those classic mini things so well. Could do with 5th gear though.

my MK2 Cooper S is similar - I do what I want with it, but everything I've done is easy for me to remove when I feel it's time, I'll restore it one day and go back to 100% stock (probably). I just avoid cutting or drilling holes in the body. It has now or has had things like - 1100S engine, supercharger, fuel injection, hydraulic handbrake, aftermarket drivers seat, various styles of wheels, single HIF44 carb.... and more other things than I can remember

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did I tell you that I won a trophy?

As well as spacer drums to match the track

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1963 Morris 850 Smoke Grey
1963 Morris 850 Shadow Blue
1965 Morris Mini Smooth Van
1966 Morris Mini Van
1969 Morris Mini Deluxe Resto
5/72 Clubman Gt

Sounds like I might be about to open Pandora's box of mods haha